In tests done with the Biologic Response Modifier Program (BRMP) of the N.C.I., Poly ICLC has been found to be the most effective B.R.M. that has been tested there. It augments MLR reaction, cytotoxic macrophages, specific cytotoxic T lymphocytes and other immune functions. When used in conjunction with a non effective tumor vaccine, it leads to the development of specific immunity to that tumor. It is effective vs. a variety of metastatic and spontaneous tumors in mice. There have been found 2/8 partial remissions in Renal Cell Carcinoma and 2/10 partial remissions in malignant melanoma in humans--both very resistant tumors. Negative results have been found in leukemia, neuroblastoma and metastatic breast cancer. Additional studies were peripheral neuropathies (at Walter Reed and Texas Medical School, Dallas, Texas) have shown 4/4 improvements. Ten patients with multiple sclerosis in a chronic declining phase have been on a study for upward of 10 months. Eight have stabilized or improved, 2 have worsened. These patients show a variety of changes in immune related functions.